Earlier seen as a solar PV technology for the rooftop solar segment, heterojunction (HJT) is now expanding its scope to the ground-mount market as well, thanks to its leading bifaciality and cost improvements. Its applications include traditional utility-scale plants, floating solar and agrivoltaics, among others.
To discuss the benefits HJT technology brings to various applications, especially with regard to levelized cost of electricity/energy (LCOE), TaiyangNews held a Special Focus Webinar on HJT Solar Application Trends In Europe on January 30, 2024. The world's largest HJT solar manufacturer Huasun Energy from China, with over 20 GW production capacity as of the end of 2023 and plans for over 40 GW by 2025, and German agrivoltaics pioneer Next2Sun joined the webinar.
Huasun Energy's Director of Business Development Europe, Christian Comes tried to break the complexity surrounding LCOE for large-scale solar power plants with his presentation.
Pointing to the little nuances that make and drive LCOE, Comes said his effort is to present enough information to make the audience take a critical look at the subject and make their own judgment, as 'malicious choices in modeling' can give any desired result.
Characterizing the calculation of actual LCOE as one of the complex processes, requiring people of different backgrounds and actual duration of the time frame that makes the exercise more complex, Comes delved deep into the so-called 'technical LCOE' that simplifies the estimation of the power production cost of a PV system. The approach omits the financial cost and depreciation or inflation, while only considering simplified OpEx and predefined period of construction that still enables comparing different configurations from an engineering point of view.
Taking CapEx-OpEx-Performance as the base of any LCOE calculation, Comes explained that system characteristics such as efficiency, cost, quality, reliability, technology and degradation/reliability are all integral to the calculation of LCOE. He shared that while solar modules constitute a very small part of the total CapEx of a solar power plant, their efficiency can impact the overall performance and cost of a system. Hence, it becomes critical to choose modules that deliver.
Comes presented 2 scenarios. One titled as same BOS, meaning just the panels are swapped between the brands, keeping all the technicalities the same. The second approach is to optimize the system characteristics for each solar module, which is relatively more comprehensive.
Taking the first instance, he made a comparison between the most common HJT and TOPCon modules from the marketplace. The power bin for Huasun's HJT ranges between 715 and 720 are the most common and 690 for TOPCon, according to Comes. For a 15 MW system, the same BOS configuration, the 27 modules per each of the 830 strings remain the same in both the cases of 715 W HJT modules and 690 W TOPCon panels. However, the high power HJT module results in 5% higher power capacity, while the DC/AC ratio is slightly higher at 127% with HJT compared to 125% with TOPCon.
The performance ratio (PR) of HJT is always higher due to better field performance characteristics; while the PR for HJT is typically 2% higher, it is reduced to 1.3% in this case as the DC/AC ratio of HJT is higher, meaning an inverter would kill some of this improvement. He added that the BOS is not optimized according to the module, meaning the absolute BOS cost would remain the same for both approaches, but would change on a per-watt basis showing HJT has 1.7 Eurocents lower and a performance benefit of 0.06 Eurocents. This adds up to more than a 2 Eurocent advantage in LCOE with HJT. When back calculating, "HJT panels priced 2 Eurocents more than TOPCon still results in lower LCOE," says Comes.
In the second scenario, when the system is optimized according to the selected module, Comes again presented 2 cases of using a string inverter and a central inverter. In the case of a multi-megawatt block design with a fully optimized tracker, AC/AC ratio, combiner box, layout and DC wiring design for a central inverter, Comes showed the simulation results for a 1P tracker system in a location in Spain. Taking the module characteristics of a 720 W HJT module priced 0.9 Eurocents higher than 12 Eurocents for a 690 W TOPCon module, the CapEx is marginally lower for the system using HJT modules, while the LCOE is 0.8 Eurocents lower than TOPCon.
The scenario changes slightly when using a string inverter, as the number of modules per string may not be the same as that for a central inverter. That's because maximum utilization of inverter capacity may adversely affect the DC/AC ratio. Also dedicating an inverter per tracker also reduces the number of modules. With optimized system parameters, the simulation results showed that the CapEx for the TOPCon system is slightly lower than HJT, while still showing the lower LCOE of 0.7 Euro cents.
Comes stressed that HJT modules save on BOS costs for utility-scale solar, thanks to the higher efficiency, and higher yield which will give an equivalent saving in CapEx.
In his presentation, Comes also reflected on the realistic power ratings for various module sizes. He said Huasun's HJT modules offer much higher power output than TOPCon or PERC modules for G10-144, 210R-132 and G12-132 sizes.
In conclusion, Comes stressed that HJT is offsetting roundabout the installation cost with a higher price, and that it is planned to have a very small cost compared to TOPCon in 2025. For any configurations made by developers and EPCs for large-scale power plants for the future, all of the configurations will have a lower total system cost with HJT.
According to him, HJT is expected to match the manufacturing cost of TOPCon by 2025-end as further technological advancements take place, and he recommended using HJT modules for utility-scale projects being planned for 2025-26.
As per Huasun's technology roadmap, it plans to implement important cost reduction measures in mass production like zero busbar, and thinner wafers that will make its HJT modules come very close to the TOPCon manufacturing cost by the end of next year.
Currently operating a 20 GW HJT production capacity in China, Huasun is the largest HJT manufacturer and the company also has in-house ingot and wafer production.
In his presentation, Next2Sun's Technical Project Manager Peter Bendix explained the reasons behind the German 'inventor' of vertical racking system using HJT solar panels exclusively for all its installations.
Nex2Sun installs solar panels in a vertical fashion like a fence, leaving a row space of usually 10 m to 12 m. This allows for agricultural activities to go on uninterrupted since a typical installation can cover less than 1% of the available land, meaning dual usage of land. These vertical bifacial agrivoltaics can perform better than conventional south PV in many regions of the world, Bendix added. This model works best with bifacial HJT panels since they offer high bifaciality.
The most important benefit of vertical bifacial installations of Next2Sun is that with an east and west configuration, the power generation is highest during morning and evening times. This ensures a power generation profile reflecting the demand pattern of the grid, unlike the common south oriented PV plants with peak power generation at noon. This simply works best when it comes to sale of power generated in the market since one can get better price for peak morning and evening generation, vis-à-vis south oriented installations. He showed an example of price fluctuation of power for a day in June 2021, a trend that still holds good, in which the generation pattern of the Next2Sun system closely follows the peak price of energy price in spot market.
In today's context, Bendix estimates that the power produced by the Next2Sun system has 10% higher market value than the traditional solar system, which already compensates its 10% higher LCOE. On the other hand, the power produced by a traditional system on a summer mid-day, i.e., at its peak, may not earn any revenue due to oversupply.
The system configuration addresses another bottleneck of PV installation – grid availability. Due to the anticyclic power generation profile, the Next2Sun technology enables installing 3 times higher capacity to be connected to the same grid connection point.
Panel discussion
Moderated by TaiyangNews Senior News Editor Anu Bhambhani, the panel discussion revolved around the various value additions of HJT for different applications.
Christian Comes of Huasun Energy said even though HJT was considered a great fit only for rooftop PV applications till recently, consumers here look for high efficiency and not higher bifaciality. HJT and back contact cells will probably be a great fit for this segment moving forward.
Next2Sun's Peter Bendix vouched for the HJT technology for vertical installations that the company undertakes thanks to the higher bifaciality.
As for large projects at utility scale, there are several projects being planned as we speak thanks to the higher bifaciality, said Comes. Developers, EPCs and IPPs stayed away from HJT for larger installations precisely because of high cost despite the obvious advantages it offers. As its cost has come down, it has started to make sense.
However, he added that the market acceptance of HJT will increase when the costs come down. Huasun will be open to expand the use of its HJT panels to other applications as well, starting with floating solar for which it has a dedicated module range.